Async programming, short for asynchronous programming, is one of those concepts that might sound intimidating at first but becomes indispensable once you grasp its power.

In today’s world, where speed and responsiveness are everything, understanding how to effectively use async programming is an essential skill. Whether you’re building a web app, mobile app, a game or even working on backend services, async programming allows you to optimize performance and enhance user experience.

In this post, I’ll cover the basic concepts of async programming which apply to all languages, so if you’re new to async or needs a reinforcement, this is a good starting point.

At its core, async programming is a method that allows your program to initiate a potentially long-running task and then move on to other tasks without waiting for that first one to finish. This approach contrasts with synchronous programming, where tasks are executed one after another, meaning your program could be stuck waiting for one task to complete before moving on to the next.

Imagine you’re making an API call, a common task in any modern application. This call involves traversing networks, passing through firewalls, encrypting and decrypting data, querying databases, and more.

While this process might only take a second or less, in computer time, even a second can feel like an eternity, especially when users expect instantaneous responses. This is where async programming shines, allowing the program to continue running other tasks while waiting for the API call to complete in the background.

Why Should You Use Async Programming?

There are three primary reasons to incorporate async programming into your projects:

1. Improved Performance: Although async calls don’t necessarily run faster than synchronous ones, they allow your application to do more in less time. By not waiting for one task to finish before starting another, you can improve the overall throughput of your application.

2. Better Resource Utilization: Async programming leverages non-blocking operations, ensuring that your CPU isn’t sitting idle while waiting for a task to complete. Instead, it can work on other tasks, making the most out of the processing power at its disposal.

3. Enhanced User Experience: Nobody likes staring at loading spinners. Async programming helps create a smoother, more responsive user experience by allowing users to continue interacting with your application while it handles background tasks.

While async programming sounds great, it’s important to know when to use it and when it’s better to stick with synchronous (sync) programming.

Sync programming is straightforward: tasks are completed one after the other. This approach is efficient for CPU-bound operations like data processing or heavy computations where tasks need to be executed sequentially to maintain performance.

Async programming, on the other hand, is ideal for I/O-bound operations such as network requests, file handling, or database interactions. However, there’s a trade-off. Async programming introduces overhead, as your program needs to manage checkpoints, set up alerts for task completions, and handle state management when resuming tasks. This makes it less efficient for quick, CPU-bound tasks that don’t benefit from parallel execution.

While there are nuances, most modern programming languages, such as Python, JavaScript, C#, Java, and Rust, have adopted a similar pattern for implementing async programming. The magic usually happens with two keywords: `async` and `await`.

Using the `async` keyword signals that a function contains asynchronous calls inside, allowing the language runtime to set up the necessary infrastructure. The `await` keyword is used to then actually initiate an async call. When the runtime encounters `await`, it creates a save point in the code and resumes from that point once the background task completes.

If you’re intrigued by async programming and want to master it, particularly in Python, stay tuned! I’m working on a comprehensive tutorial that will take you from zero to hero in async code.

I also made a counterpart video covering some of the points in this post which could be helpful to make things clear:

Thank you for reading! If you found this post helpful, share it with others and stay connected for more insights on async programming.